This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 1. Opioid use during treatment and at the six-month follow-up evaluation will be significantly lower for the depot naltrexone group than for the psychosocial treatment only group. 2. Volunteers randomized to the depot naltrexone condition will have fewer new arrests and lower reincarceration rates over a six-month evaluation period than volunteers in the psychosocial treatment only group. 3. Treatment attendance and retention rates will be higher for the depot naltrexone group than for the psychosocial treatment only group. 4. Men and women randomized to the depot naltrexone condition will show greater improvements over a one year evaluation period in psychosocial and medical/psychiatric functioning. Secondary Hypothesis: Individuals with high levels of antisociality/criminality or high psychiatric severity will have poorer treatment responses to naltrexone, particularly as reflected in higher new arrests and reincarceration rates, than those relatively low in these characteristics. Cost-related Hypotheses: The net incremental benefits (i.e., costs avoided) of naltrexone treatment realized in the form of reduced legal and medical expenditure will exceed the incremental costs of psychosocial treatment alone. Specific Aims To test our hypothesis, we will conduct a small pilot study to demonstrate the feasibility and acceptability of both the depot naltrexone and psychosocial intervention with probation/parolees or drug court participants with a history of opioid dependence. Using the preliminary data we collect, we will collaborate with other sites to develop a cooperative R01 grant application.